The present invention relates to the general field of annular combustion chambers for turbine engines equipped with a single-piece protective cowling for the fuel injection systems.
A turbine engine annular combustion chamber is generally made up of two longitudinal walls generated by revolution (an outer wall and an inner wall) which are connected upstream by a transverse wall forming the chamber bottom.
The present invention relates more particularly to combustion chambers that also comprise a single-piece cowling mounted upstream of the chamber bottom. The cowling is used in particular to protect the fuel injection systems which are mounted on the chamber bottom.
Assembling these different elements of the combustion chamber is carried out by means of bolt connections mounted at the inner and outer walls. More precisely, the chamber bottom and the cowling each comprise an inner flange and an outer flange on which respectively the inner wall and the outer wall of the combustion chamber are fixed by bolt connections, these longitudinal walls being inserted between the cowling and the chamber bottom. Thus, the same bolt connection passes through all the following: one of the longitudinal walls, the chamber bottom and the cowling of the combustion chamber.
In practice, this type of combustion chamber architecture poses many problems. In particular, the different elements of the combustion chamber have large manufacturing tolerances, which leads to stacking up of the tolerances resulting in poor closing up between these elements when the combustion chamber is being assembled, which creates a loss as regards the clamping transiting between the flanges. This is because the part of the clamping which is used for deforming the chamber is subtracted from the force of reactions between its components. When this reaction force decreases, the force necessary for making the parts slide among themselves is therefore less. An additional clamping torque is therefore necessary for taking up the play due to the manufacturing tolerances of the components and thus keeping the correct clamping force for passage of the sliding forces transiting in the connection. Therefore, during operation, the vibrations caused by the combustion of gases inside the combustion chamber lead to the formation of cracks in the region of the bolt connections on the cowling and/or the chamber bottom. Such cracks are particularly prejudicial to the service life of the combustion chamber.